U.S. patent application number 15/651323 was filed with the patent office on 2018-02-15 for propylene-olefin copolymers and methods for making the same.
The applicant listed for this patent is ExxonMobil Chemical Patents Inc.. Invention is credited to John R. Hagadorn, Gregory K. Hall, Peijun Jiang, Arturo Leyva, Sarah J. Mattler, Alexander I. Norman, Ying Ying Sun, Andy H. Tsou.
Application Number | 20180044514 15/651323 |
Document ID | / |
Family ID | 61158598 |
Filed Date | 2018-02-15 |
United States Patent
Application |
20180044514 |
Kind Code |
A1 |
Norman; Alexander I. ; et
al. |
February 15, 2018 |
Propylene-Olefin Copolymers and Methods for Making the Same
Abstract
Provided is a composition having 70 wt % to 90 wt % of a first
propylene-olefin copolymer component having an ethylene content of
15 to 21 wt %; and 10 wt % to 30 wt % of a second propylene-olefin
copolymer component having an ethylene content of 6 to 10 wt %;
wherein the weight average molecular weight of the first component
is 250,000 to 1,780,000 g/mol higher than the weight average
molecular weight of the second component; wherein the reactivity
ratio product of the first component is less than 0.75; wherein the
reactivity ratio product of the second component is greater than or
equal to 0.75.
Inventors: |
Norman; Alexander I.;
(Houston, TX) ; Hall; Gregory K.; (Humble, TX)
; Hagadorn; John R.; (Houston, TX) ; Tsou; Andy
H.; (Houston, TX) ; Jiang; Peijun; (League
City, TX) ; Sun; Ying Ying; (shanghai, CN) ;
Mattler; Sarah J.; (League City, TX) ; Leyva;
Arturo; (League City, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ExxonMobil Chemical Patents Inc. |
Baytown |
TX |
US |
|
|
Family ID: |
61158598 |
Appl. No.: |
15/651323 |
Filed: |
July 17, 2017 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
62375163 |
Aug 15, 2016 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08L 23/16 20130101;
C08F 2500/01 20130101; C08L 23/14 20130101; C08F 210/16 20130101;
C08L 2205/025 20130101; C08F 2500/02 20130101; C08F 210/16
20130101; C08F 4/64148 20130101; C08F 210/16 20130101; C08F 4/65925
20130101; C08F 210/06 20130101; C08F 210/16 20130101; C08F 2500/12
20130101; C08F 2500/15 20130101; C08F 2500/01 20130101; C08F 210/06
20130101; C08F 210/16 20130101; C08F 2500/12 20130101; C08F 2500/15
20130101; C08F 2500/02 20130101; C08L 23/14 20130101; C08L 23/14
20130101 |
International
Class: |
C08L 23/16 20060101
C08L023/16; C08F 210/16 20060101 C08F210/16 |
Claims
1. A composition comprising (a) from about 70 wt % to about 90 wt %
of a first propylene alpha-olefin copolymer component based on the
weight of the composition, wherein the first component has an
ethylene content of about 15 wt % to about 21 wt %; and (b) from
about 10 wt % to about 30 wt % of a second propylene alpha-olefin
copolymer component based on the weight of the composition, wherein
the second component has an ethylene content of about 6 wt % to
about 10 wt %; wherein the weight average molecular weight of the
first component is about 250,000 to about 1,780,000 g/mol higher
than the weight average molecular weight of the second component;
wherein the reactivity ratio product of the first component is less
than 0.75; wherein the reactivity ratio product of the second
component is greater than or equal to 0.75; and wherein the
composition has at least one of the following properties: (i) a
tension set of less than about 15%; (ii) a top load of less than
about 8 N; (iii) a retractive force of greater than about 3.5 N; or
(iv) a hysteresis of less than about 35%.
2. The composition of claim 1, having: (i) a tension set of less
than about 15%; (ii) a top load of less than about 8 N; (iii) a
retractive force of greater than about 3.5 N; and (iv) a hysteresis
of less than about 35%.
3. The composition of claim 1, wherein the first component has a
weight average molecular weight of about 400,000 to about 1,800,000
g/mol and the second component has a weight average molecular
weight of about 20,000 to about 150,000 g/mol.
4. A process to make a composition, comprising the steps of: (a)
contacting propylene and optional alpha-olefin comonomer with a
first catalyst, wherein the first catalyst is a transition metal
complex that does not have any pi-coordinated cyclopentadienyl
anion donors, to form a first propylene alpha-olefin copolymer
component; (b) contacting propylene and optional comonomer with a
second catalyst different from the first catalyst, to form a second
propylene alpha-olefin copolymer component; and (c) recovering a
composition comprising from about 70 wt % to about 90 wt % of the
first component and from about 10 wt % to about 30 wt % of the
second component, based on the total weight of the composition.
5. The process of claim 4, wherein the first catalyst is a pyridyl
diamide catalyst, having the structural formula: ##STR00004##
wherein M is a Group 3-12 metal; E is selected from carbon,
silicon, or germanium; X is an anionic leaving group, such as, but
not limited to alkyl, aryl, hydride, alkylsilane, fluoride,
chloride, bromide, iodide, triflate, carboxylate, alkylsulfonate,
amide, alkoxide, and hydroxide; L is a neutral Lewis base, such as,
but not limited to ether, amine, thioether; R.sup.1 and R.sup.13
are independently selected from the group consisting of
hydrocarbyls, substituted hydrocarbyls, and silyl groups; R.sup.2
through R.sup.12 are independently selected from the group
consisting of hydrogen, hydrocarbyls, alkoxy, silyl, amino,
aryloxy, substituted hydrocarbyls, halogen, and phosphino; n is 1
or 2 or 3; m is 0, 1, or 2; and two X groups may be joined together
to form a dianionic group; two L groups may be joined together to
form a bidentate Lewis base; an X group may be joined to an L group
to form a monoanionic bidentate group; any two adjacent R groups
(e.g. R.sup.7 & R.sup.8, R.sup.10 & R.sup.11, etc.) may be
joined to form a substituted or unsubstituted hydrocarbyl or
heterocyclic ring, where the ring has 5, 6, 7, or 8 ring atoms and
where substitutions on the ring can join to form additional rings;
(preferably an aromatic ring, a six membered aromatic ring with the
joined R.sup.7R.sup.8 group being --CH.dbd.CHCH.dbd.CH--); R.sup.10
and R.sup.11 may be joined to form a ring (preferably a five
membered ring with the joined R.sup.10R.sup.11 group being
--CH.sub.2CH.sub.2--, a six membered ring with the joined
R.sup.10R.sup.11 group being --CH.sub.2CH.sub.2CH.sub.2--).
6. The process of claim 4, further comprising polymerizing the
first propylene alpha-olefin copolymer component in a first reactor
and polymerizing the second propylene alpha-olefin copolymer
component in a second reactor.
7. The process of claim 6, wherein the first reactor and the second
reactor are the same or different.
8. The process of claim 6, wherein the first reactor and the second
reactor are arranged in series or parallel.
9. The process of claim 8, wherein the series reactors are
connected in fluid communication.
10. The process of claim 6, wherein the first reactor and the
second reactor are continuous stirred tank or tubular reactors.
11. The process of claim 6, wherein the first reactor and the
second reactor are selected from the group consisting of
solution-phase reactor and gas-phase reactor.
12. The process of claim 4, further comprising pelletizing the
composition.
13. A composition made according to the process of claim 4.
14. A composition made according to the process of claim 13,
wherein the first component has an ethylene content of about 15 wt
% to about 20 wt % and the second component has an ethylene content
of about 6 wt % to about 10 wt %.
15. The composition of claim 13, wherein the weight average
molecular weight of the first component is about 250,000 to about
1,780,000 g/mol higher than the weight average molecular weight of
the second component.
16. The composition of claim 13, wherein the reactivity ratio
product of the first component is less than 0.75 and the reactivity
ratio product of the second component is greater than 0.75.
17. The composition of claim 13, having at least one of the
following properties: (i) a tension set of less than about 15%;
(ii) a top load of less than about 8 N; (iii) a retractive force of
greater than about 3.5 N; or (iv) a hysteresis of less than about
35%.
18. The composition of claim 13, having: (i) a tension set of less
than about 15%; (ii) a top load of less than about 8 N; (iii) a
retractive force of greater than about 3.5 N; and (iv) a hysteresis
of less than about 35%.
19. The composition of claim 13, wherein the first component has a
weight average molecular weight of about 400,000 to about 1,800,000
g/mol and the second component has a weight average molecular
weight of about 20,000 to about 150,000 g/mol.
20. A personal hygiene material, packaging material, roofing
material, tape material, flooring material, or film, comprising the
composition according to claim 1.
Description
PRIORITY CLAIM
[0001] This application claims priority to and benefit of U.S. Ser.
No. 62/375,163, filed Aug. 15, 2016 and is incorporated herein by
reference in its entirety.
FIELD
[0002] This invention is related to propylene olefin copolymers
that are a blend of high and low molecular weight propylene olefin
copolymers to produce a blend useful for soft, elastic
applications.
BACKGROUND
[0003] Polyolefin polymers and polymer blends are known for their
utility in a wide variety of applications. In particular, many
polyolefin polymers, including copolymers of propylene with other
olefins such as ethylene, are well suited for use in applications
requiring good stretchability, elasticity, and strength. Such
polymers often comprise a blend of two or more propylene
copolymers, and may be manufactured by physically blending two or
more copolymers, or by reactor blending of the copolymers.
[0004] Many polyolefin blends known in the prior art are formed
into pellets for intermediate storage purposes before being shaped
into articles such as fibers, films, nonwovens, extruded coatings,
and molded articles. Some of these compositions, however, are known
to exhibit poor pellet stability over extended periods of time,
leading to agglomeration of pellets and resulting in pellet batches
that a do not flow/pour well, particularly after storage and
shipping under hot climate conditions. Further, the typically low
melting points of such known polymer blends often lead to
flattening or other deformation of polymer pellets during long-term
storage, which also negatively affects the ability of the polymer
pellets to be free-flowing. While blending such polyolefin
copolymers with higher-crystallinity components has been shown to
improve stability properties of the polymer pellets, such pellets
lose some of their elasticity and still have a tendency to
agglomerate during shipping and long-term storage, thus presenting
processing issues where free-flowing pellets are required.
[0005] As a result, many known polyolefin blend pellets are blended
with approximately 10 wt % of a crystalline random
propylene-ethylene copolymer, as disclosed in U.S. Pat. Nos.
7,026,405 and 7,803,876. While the resultant polyolefin are pellet
stable, they are generally less elastic with a higher tension set,
top load, and hysteresis as compared to the original polyolefin
blend pellets without the random copolymer. Accordingly, such
products have limited utility in applications where enhanced
elasticity is required.
[0006] The inventors have discovered that incorporating a high
molecular weight pyridyl diamido-based catalyzed copolymer with a
low molecular weight metallocene catalyzed copolymer can produce a
balance of a pellet stable bimodal propylene olefin copolymer
having suitable elastic recovery properties. In contrast to
products prepared with a random propylene-ethylene copolymer, the
olefin copolymers of the invention have a broad split in molecular
of each component but a narrow split in olefin content of each
component.
SUMMARY
[0007] In one aspect, provided herein is a composition comprising
from about 70 wt % to about 90 wt % of a first propylene
alpha-olefin copolymer component having an ethylene content of
about 15 to about 21 wt %; and from about 10 wt % to about 30 wt %
of a second propylene alpha-olefin copolymer component having an
ethylene content of about 6 to about 10 wt %; wherein the weight
average molecular weight of the first component is about 250,000 to
about 1,780,000 g/mol higher than the weight average molecular
weight of the second component wherein the reactivity ratio product
of the first component is less than 0.75; wherein the reactivity
ratio product of the second component is greater than or equal to
0.75; and wherein the composition has at least one of the following
properties: (i) a tension set of less than about 15%; (ii) a top
load of less than about 8 N; (iii) a retractive force of greater
than about 3.5 N; or (iv) a hysteresis of less than about 35%.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] The FIGURE shows the crystallization kinetics of a
comparative propylene-based elastomer and three inventive propylene
olefin copolymers.
DETAILED DESCRIPTION
[0009] Various specific embodiments and versions of the present
invention will now be described, including preferred embodiments
and definitions that are adopted herein. While the following
detailed description gives specific preferred embodiments, those
skilled in the art will appreciate that these embodiments are
exemplary only, and that the present invention can be practiced in
other ways. Any reference to the "invention" may refer to one or
more, but not necessarily all, of the embodiments defined by the
claims. The use of headings is for purposes of convenience only and
does not limit the scope of the present invention.
[0010] All numerical values within the detailed description and the
claims herein are modified by "about" or "approximately" the
indicated value, and take into account experimental error and
variations that would be expected by a person having ordinary skill
in the art.
[0011] As used herein, the term "copolymer" is meant to include
polymers having two or more monomers, optionally, with other
monomers, and may refer to interpolymers, terpolymers, etc. The
term "polymer" as used herein includes, but is not limited to,
homopolymers, copolymers, terpolymers, etc., and alloys and blends
thereof. The term "polymer" as used herein also includes impact,
block, graft, random, and alternating copolymers. The term
"polymer" shall further include all possible geometrical
configurations unless otherwise specifically stated. Such
configurations may include isotactic, syndiotactic and atactic
symmetries. The term "blend" as used herein refers to a mixture of
two or more polymers. The term "elastomer" shall mean any polymer
exhibiting some degree of elasticity, where elasticity is the
ability of a material that has been deformed by a force (such as by
stretching) to return at least partially to its original dimensions
once the force has been removed.
[0012] The term "alpha-olefin" includes ethylene.
[0013] The term "monomer" or "comonomer," as used herein, can refer
to the monomer used to form the polymer, i.e., the unreacted
chemical compound in the form prior to polymerization, and can also
refer to the monomer after it has been incorporated into the
polymer, also referred to herein as a "[monomer]-derived unit".
Different monomers are discussed herein, including propylene
monomers, ethylene monomers, and diene monomers.
[0014] "Reactor grade," as used herein, means a polymer that has
not been chemically or mechanically treated or blended after
polymerization in an effort to alter the polymer's molecular
structure such as average molecular weight, molecular weight
distribution, or viscosity. Particularly excluded from those
polymers described as reactor grade are those that have been
visbroken or otherwise treated or coated with peroxide or other
prodegradants. For the purposes of this disclosure, however,
reactor grade polymers include those polymers that are reactor
blends.
[0015] "Reactor blend," as used herein, means a blend of two or
more polymers produced in situ as the result of sequential or
parallel polymerization of one or more monomers with the formation
of one polymer in the presence of another, or by solution blending
polymers made separately in parallel reactors. Reactor blends may
be produced in a single reactor, a series of reactors, or parallel
reactors and are reactor grade blends. Reactor blends may be
produced by any polymerization method, including batch,
semi-continuous, or continuous systems. Particularly excluded from
"reactor blend" polymers are blends of two or more polymers in
which the polymers are blended ex situ, such as by physically or
mechanically blending in a mixer, extruder, or other similar
device.
Propylene Olefin Copolymers
[0016] The propylene olefin copolymer of the invention comprises a
blend of a first propylene olefin component and a second propylene
olefin component. The first component is present in the amount of
about 70 wt % to about 90 wt % of the copolymer and the second
component is present in the amount of about 10 wt % to about 30 wt
% of the copolymer. The olefin comonomer units for each component
may be derived from ethylene, butene, pentene, hexene,
4-methyl-1-pentene, octene, or decene. In preferred embodiments the
comonomer is ethylene. In some embodiments, each of the components
consists essentially of propylene and ethylene derived units, or
consists only of propylene and ethylene derived units. Some of the
embodiments described below are discussed with reference to
ethylene as the comonomer, but the embodiments are equally
applicable to other copolymers with other higher .alpha.-olefin
comonomers.
[0017] The copolymer may include at least about 5 wt %, at least
about 7 wt %, at least about 9 wt %, at least about 10 wt %, at
least about 12 wt %, at least about 13 wt %, at least about 14 wt
%, at least about 15 wt %, or at least about 16 wt %,
.alpha.-olefin-derived units, based upon the total weight of the
copolymer. The copolymer may include up to about 30 wt %, up to
about 25 wt %, up to about 22 wt %, up to about 20 wt %, up to
about 19 wt %, up to about 18 wt %, or up to about 17 wt %,
.alpha.-olefin-derived units, based upon the total weight of the
copolymer. In some embodiments, the copolymer may comprise from
about 5 to about 30 wt %, from about 6 to about 25 wt %, from about
7 wt % to about 20 wt %, from about 10 to about 19 wt %, from about
12 wt % to about 19 wt %, or from about 15 wt % to about 18 wt %,
or form about 16 wt % to about 18 wt %, .alpha.-olefin-derived
units, based upon the total weight of the copolymer.
[0018] The copolymer may include at least about 70 wt %, at least
about 75 wt %, at least about 78 wt %, at least about 80 wt %, at
least about 81 wt %, at least about 82 wt %, or at least 83 wt %,
propylene-derived units, based upon the total weight of the
copolymer. The copolymer may include up to about 95 wt %, up to
about 93 wt %, up to about 91 wt %, up to about 90 wt %, up to
about 88 wt %, or up to about 87 wt %, or up to about 86 wt %, or
up to about 85 wt %, or up to about 84 wt %, propylene-derived
units, based upon the total weight of the copolymer.
[0019] The copolymers can be characterized by a melting point (Tm),
which can be determined by differential scanning calorimetry (DSC).
Using the DSC test method described herein, the melting point is
the temperature recorded corresponding to the greatest heat
absorption within the range of melting temperature of the sample,
when the sample is continuously heated at a programmed rate. When a
single melting peak is observed, that peak is deemed to be the
"melting point." When multiple peaks are observed (e.g., principle
and secondary peaks), then the melting point is deemed to be the
highest of those peaks. It is noted that due to the
low-crystallinity of many copolymers, the melting point peak may be
at a low temperature and be relatively flat, making it difficult to
determine the precise peak location. A "peak" in this context is
defined as a change in the general slope of the DSC curve (heat
flow versus temperature) from positive to negative, forming a
maximum without a shift in the baseline where the DSC curve is
plotted so that an endothermic reaction would be shown with a
positive peak.
[0020] As used herein, the "glass transition temperature" (Tg) is
measured using dynamic mechanical analysis. This test provides
information about the small-strain mechanical response of a sample
as a function of temperature over a temperature range that includes
the glass transition region and the visco-elastic region prior to
melting. Specimens are tested using a commercially available DMA
instrument (e.g., TA Instruments DMA 2980 or Rheometrics RSA)
equipped with a dual cantilever test fixture. The specimen is
cooled to -130.degree. C. then heated to 60.degree. C. at a heating
rate of 2.degree. C./min while subjecting to an oscillatory
deformation at 0.1% strain and a frequency of 6.3 rad/sec.
[0021] The copolymer can have a triad tacticity (mm tacticity), as
measured by 13C NMR, of 75% or greater, 80% or greater, 85% or
greater, 90% or greater, 92% or greater, 95% or greater, or 97% or
greater. In one or more embodiments, the triad tacticity may range
from about 75% to about 99%, from about 80% to about 99%, from
about 85% to about 99%, from about 90% to about 99%, from about 90%
to about 97%, or from about 80% to about 97%. Triad tacticity is
determined by the methods described in U.S. Pat. No. 7,232,871.
[0022] Propylene crystallinity is probed using X-ray scattering
methods. Since polypropylene is a semi-crystalline polymer, the
crystal structure can be resolved using X-ray diffraction (XRD) or
Wide-Angle X-ray Scattering (WAXS). The unit cells of the
crystalline polymer are the building blocks of the crystalline
lamellae: planar sheets of crystalline material. Since not all
polymer chains can crystallize, amorphous chains also exist and
these typically are found in between stacks of crystalline
lamellae. WAXS can probe the extent to which these polymer chains
crystallize since the data will contain information regarding
crystalline and amorphous morphology. WAXS also can determine
crystalline orientation and crystallite size. All wide-angle X-ray
scattering (WAXS) were performed using an in-house SAXSLAB Ganesha
300XL+. Polymer pellet samples were melt pressed into discs
approximately 0.5 mm thick from a melt of 190.degree. C. Samples
were cooled in air over 7 days and then placed directly in the path
of the incident X-ray beam. The incident wavelength was 0.154 nm
from a CuKc microfocus sealed tube source (Xenocs). All samples
were collected at sample-to-detector positions of 91 mm and were
held in a vacuum to minimize air scatter. The SAXS and WAXS were
recorded using a Dectris Pilatus. Sample to detector distance was
calibrated using a Silver Behenate standard. A 0-360 integration
was performed on the 2D scattering patterns. The Intensities were
recorded as a function of scattering vector, q, where q=4.pi. sin
.theta./.lamda. (.theta. is the scattering angle and X is the
incident wavelength) and the scattering vector q is also defined as
q=2.pi./d where d is a distance in real space: unit cell dimension
from WAXS, and inter-lamellae spacing from SAXS.
[0023] All data were corrected for transmission, background
scattering and detector non-linearity.
[0024] The crystallinity of the film samples is obtained from WAXS:
unit cell type and overall extent of crystallinity. WAXS and SAXS
patterns were collapsed to an I(q) vs q plot. The overall degree of
crystallinity of the film samples was determined by taking the
ratio of the peak areas of the (110), (040), (130), (111) and (131)
(which were fit to a Gaussian function) to the total area
underneath the 1D WAXS profile[1]. The amorphous region was also
fit to a Gaussian curve. See Ryan, A. J., et al., A synchrotron
X-ray study of melting and recrystallization in isotactic
polypropylene. Polymer, 1997, 38(4): p. 759-768.
[0025] The comonomer content and sequence distribution of the
polymers can be measured using .sup.13C nuclear magnetic resonance
(NMR) by methods well known to those skilled in the art. Comonomer
content of discrete molecular weight ranges can be measured using
methods well known to those skilled in the art, including Fourier
Transform Infrared Spectroscopy (FTIR) in conjunction with samples
by GPC, as described in Wheeler and Willis, Applied Spectroscopy,
1993, Vol. 47, pp. 1128-1130. For a propylene ethylene copolymer
containing greater than 75 wt % propylene, the comonomer content
(ethylene content) of such a polymer can be measured as follows: A
thin homogeneous film is pressed at a temperature of about
150.degree. C. or greater, and mounted on a Perkin Elmer PE 1760
infrared spectrophotometer. A full spectrum of the sample from 600
cm-1 to 4000 cm-1 is recorded and the monomer weight percent of
ethylene can be calculated according to the following equation:
Ethylene wt %=82.585-111.987X+30.045X2, where X is the ratio of the
peak height at 1155 cm-1 and peak height at either 722 cm-1 or 732
cm-1, whichever is higher. For propylene ethylene copolymers having
75 wt % or less propylene content, the comonomer (ethylene) content
can be measured using the procedure described in Wheeler and
Willis. Reference is made to U.S. Pat. No. 6,525,157 which contains
more details on GPC measurements, the determination of ethylene
content by NMR and the DSC measurements.
[0026] Mw, Mn and Mw/Mn are determined by using a High Temperature
Gel Permeation Chromatography (Agilent PL-220), equipped with three
in-line detectors, a differential refractive index detector (DRI),
a light scattering (LS) detector, and a viscometer. Experimental
details, including detector calibration, are described in: T. Sun,
P. Brant, R. R. Chance, and W. W. Graessley, Macromolecules, Volume
34, Number 19, pp. 6812-6820, (2001) and references therein. Three
Agilent PLgel 10 .mu.m Mixed-B LS columns are used. The nominal
flow rate is 0.5 mL/min, and the nominal injection volume is 300
.mu.L. The various transfer lines, columns, viscometer and
differential refractometer (the DRI detector) are contained in an
oven maintained at 145.degree. C. Solvent for the experiment is
prepared by dissolving 6 grams of butylated hydroxytoluene as an
antioxidant in 4 liters of Aldrich reagent grade
1,2,4-trichlorobenzene (TCB). The TCB mixture is then filtered
through a 0.1 .mu.m Teflon filter. The TCB is then degassed with an
online degasser before entering the GPC-3D. Polymer solutions are
prepared by placing dry polymer in a glass container, adding the
desired amount of TCB, then heating the mixture at 160.degree. C.
with continuous shaking for about 2 hours. All quantities are
measured gravimetrically. The TCB densities used to express the
polymer concentration in mass/volume units are 1.463 g/ml at room
temperature and 1.284 g/ml at 145.degree. C. The injection
concentration is from 0.5 to 2.0 mg/ml, with lower concentrations
being used for higher molecular weight samples. Prior to running
each sample the DRI detector and the viscometer are purged. Flow
rate in the apparatus is then increased to 0.5 ml/minute, and the
DRI is allowed to stabilize for 8 hours before injecting the first
sample. The LS laser is turned on at least 1 to 1.5 hours before
running the samples. The concentration, c, at each point in the
chromatogram is calculated from the baseline-subtracted DRI signal,
I.sub.DRI, using the following equation:
c=K.sub.DRII.sub.DRI/(dn/dc)
where K.sub.DRI is a constant determined by calibrating the DRI,
and (dn/dc) is the refractive index increment for the system. The
refractive index, n=1.500 for TCB at 145.degree. C. and A=690 nm.
Units on parameters throughout this description of the GPC-3D
method are such that concentration is expressed in g/cm.sup.3,
molecular weight is expressed in g/mole, and intrinsic viscosity is
expressed in dL/g.
[0027] The LS detector is a Wyatt Technology High Temperature DAWN
HELEOS. The molecular weight, M, at each point in the chromatogram
is determined by analyzing the LS output using the Zimm model for
static light scattering (M. B. Huglin, LIGHT SCATTERING FROM
POLYMER SOLUTIONS, Academic Press, 1971):
K o c .DELTA. R ( .theta. ) = 1 MP ( .theta. ) + 2 A 2 c .
##EQU00001##
Here, .DELTA.R(.theta.) is the measured excess Rayleigh scattering
intensity at scattering angle .theta., c is the polymer
concentration determined from the DRI analysis, A.sub.2 is the
second virial coefficient. P(.theta.) is the form factor for a
monodisperse random coil, and K.sub.o is the optical constant for
the system:
K o = 4 .pi. 2 n 2 ( dn / dc ) 2 .lamda. 4 N A ##EQU00002##
where N.sub.A is Avogadro's number, and (dn/dc) is the refractive
index increment for the system, which take the same value as the
one obtained from DRI method. The refractive index, n=1.500 for TCB
at 145.degree. C. and .lamda.=657 nm.
[0028] A high temperature Viscotek Corporation viscometer, which
has four capillaries arranged in a Wheatstone bridge configuration
with two pressure transducers, is used to determine specific
viscosity. One transducer measures the total pressure drop across
the detector, and the other, positioned between the two sides of
the bridge, measures a differential pressure. The specific
viscosity, .eta..sub.S, for the solution flowing through the
viscometer is calculated from their outputs. The intrinsic
viscosity, [.eta.], at each point in the chromatogram is calculated
from the following equation:
.eta..sub.S=c[.eta.]+0.3(c[.eta.]).sup.2
where c is concentration and was determined from the DRI
output.
[0029] The branching index (g'.sub.vis) is calculated using the
output of the GPC-DRI-LS-VIS method as follows. The average
intrinsic viscosity, [.eta.].sub.avg, of the sample is calculated
by:
[ .eta. ] avg = c i [ .eta. ] i c i ##EQU00003##
where the summations are over the chromatographic slices, i,
between the integration limits.
[0030] The branching index g'.sub.vis is defined as:
g ' vis = [ .eta. ] avg kM v .alpha. . ##EQU00004##
M.sub.V is the viscosity-average molecular weight based on
molecular weights determined by LS analysis. Z average branching
index (g'z.sub.ave) is calculated using Ci=polymer concentration in
the slice i in the polymer peak times the mass of the slice
squared, Mi.sup.2.
[0031] All molecular weights are weight average unless otherwise
noted. All molecular weights are reported in g/mol unless otherwise
noted. Branching Index. The ethylene elastomers described herein
preferably having a branching index of greater than about 0.5. The
relative degree of branching in the propylene-olefin is determined
using a branching index factor (BI). Calculating this factor
requires a series of three laboratory measurements of polymer
properties in solutions as disclosed in VerStrate, Gary,
"Ethylene-Propylene Elastomers", Encyclopedia of Polymer Science
and Engineering, 6, 2nd edition (1986). These are: (i) Mw, GPC
LALLS, weight average molecular weight measured using a low angle
laser light scattering (LALLS) technique in combination with Gel
Permeation Chromatography (GPC) (ii) weight average molecular
weight (MwDRI) and viscosity average molecular weight (MvDRI) using
a differential refractive index (DRI) detector in combination with
GPC and (iii) intrinsic viscosity (IV) measured in decalin at
135.degree. C. The first two measurements (i and ii) are obtained
in a GPC using a filtered dilute solution of the polymer in
trichlorobenzene.
[0032] In embodiments, the weight average molecular weight of the
first polymer component is greater than that of the second polymer
component. In embodiments, the weight average molecular weight of
the first polymer component is greater than about 250,000 g/mol, or
about 500,000 g/mol, or about 750,000 g/mol, or about 1,000,000
g/mol, or about 1,500,000 g/mol, or about 1,780,000 g/mol higher
than that of the second polymer component. Preferably, the weight
average molecular weight of the first polymer component is greater
than about 400,000 g/mol, or about 450,000 g/mol, or about 500,000
g/mol to less than about 1,800,000 g/mol, or about 1,750,000 g/mol,
or about 1,500,000 g/mol. Preferably, the weight average molecular
weight of the second polymer component is greater than about 20,000
g/mol, or about 30,000 g/mol, or about 50,000 g/mol to less than
about 150,000 g/mol, or about 125,000 g/mol, or about 100,000
g/mol.
[0033] The first component of the copolymer may have a melt flow
rate (MFR), as measured according to ASTM D-1238 (2.16 kg weight @
230.degree. C.) of from less than 0.1 g/10 min to 0.3 g/10 min and
the second component of the copolymer may have a MFR of from 20
g/10 min to 15,000 g/10 min.
[0034] In preferred embodiments, the copolymer is a reactor grade
or reactor blended polymer, as defined above. That is, in preferred
embodiments, the copolymer is a reactor blend of a first polymer
component and a second polymer component. Thus, the comonomer
content of the copolymer can be adjusted by adjusting the comonomer
content of the first polymer component, adjusting the comonomer
content of second polymer component, and/or adjusting the ratio of
the first polymer component to the second polymer component present
in the copolymer.
[0035] In embodiments where the copolymer is a reactor blended
polymer, the .alpha.-olefin content of the first polymer component
("R.sub.1") may be greater than 5 wt %, greater than 7 wt %,
greater than 10 wt %, greater than 12 wt %, greater than 15 wt %,
or greater than 17 wt %, based upon the total weight of the first
polymer component. The .alpha.-olefin content of the first polymer
component may be less than 30 wt %, less than 27 wt %, less than 25
wt %, less than 22 wt %, less than 20 wt %, or less than 19 wt %,
based upon the total weight of the first polymer component. In some
embodiments, the .alpha.-olefin content of the first polymer
component may range from 5 wt % to 30 wt %, from 7 wt % to 27 wt %,
from 10 wt % to 25 wt %, from 12 wt % to 22 wt %, from 15 wt % to
20 wt %, or from 17 wt % to 19 wt %. Preferably, the first polymer
component comprises propylene and ethylene derived units, or
consists essentially of propylene and ethylene derived units.
[0036] In embodiments where the copolymer is a reactor blended
polymer, the .alpha.-olefin content of the second polymer component
("R.sub.2") may be greater than 1.0 wt %, greater than 1.5 wt %,
greater than 2.0 wt %, greater than 2.5 wt %, greater than 2.75 wt
%, or greater than 3.0 wt %, or greater than 5.0 wt %, or greater
than 6.0 wt % .alpha.-olefin, based upon the total weight of the
second polymer component. The .alpha.-olefin content of the second
polymer component may be less than 10 wt %, less than 9 wt %, less
than 8 wt %, less than 7 wt %, less than 6 wt %, or less than 5 wt
%, based upon the total weight of the second polymer component. In
some embodiments, the .alpha.-olefin content of the second polymer
component may range from 1.0 wt % to 10 wt %, or from 1.5 wt % to 9
wt %, or from 2.0 wt % to 8 wt %, or from 2.5 wt % to 7 wt %, or
from 2.75 wt % to 6 wt %, or from 3 wt % to 5 wt %. Preferably, the
second polymer component comprises propylene and ethylene derived
units, or consists essentially of propylene and ethylene derived
units.
[0037] In embodiments where the copolymer is a reactor blended
polymer, the copolymer may comprise from 1 to 25 wt % of the second
polymer component, from 3 to 20 wt % of the second polymer
component, from 5 to 20 wt % of the second polymer component, from
7 to 15 wt % of the second polymer component, from 8 to 12 wt % of
the second polymer component, or from 15 to 20 wt % of the second
polymer component, based on the weight of the copolymer, where
desirable ranges may include ranges from any lower limit to any
upper limit. The copolymer may comprise from 70 to 99 wt % of the
first polymer component, from 70 to 90 wt % of the first polymer
component, from 80 to 97 wt % of the first polymer component, from
85 to 93 wt % of the first polymer component, or from 82 to 92 wt %
of the first polymer component, based on the weight of the
copolymer, where desirable ranges may include ranges from any lower
limit to any upper limit.
[0038] Copolymerization of monomer M1 and monomer M2 leads to two
types of polymer chains--one with monomer M1 at the propagating
chain end (M1*) and other with monomer M2 (M2*). Four propagation
reactions are then possible. Monomer M1 and monomer M2 can each add
either to a propagating chain ending in monomer M1 or to one ending
in monomer M2, i.e.,
M 1 * + M 1 .fwdarw. k 11 M 1 * ##EQU00005## M 1 * + M 2 .fwdarw. k
12 M 2 * ##EQU00005.2## M 2 * + M 1 .fwdarw. k 21 M 1 *
##EQU00005.3## M 2 * + M 2 .fwdarw. k 22 M 2 * ##EQU00005.4##
where k.sub.11 is the rate constant for inserting M1 to a
propagating chain ending in M1 (i.e. M1*), k.sub.12 is the rate
constant for inserting M2 to a propagating chain ending in M1
(i.e., M1*), and so on. The monomer reactivity ratio r.sub.1 and
r.sub.2 are defined as
r 1 = k 11 k 12 ; r 2 = k 22 k 21 ##EQU00006##
r.sub.1 and r.sub.2 as defined above is the ratio of the rate
constant for a reactive propagating species adding its own type of
monomer to the rate constant for its addition of the other monomer.
The tendency of two monomers to copolymerize is noted by values of
r.sub.1 and r.sub.2. An r.sub.1 value greater than unity means that
M1* preferentially inserts M1 instead of M2, while an r.sub.1 value
less than unity means that M1* preferentially inserts M2. An
r.sub.1 value of zero would mean that M1 is incapable of undergoing
homopolymerization.
[0039] The preferential insertions of two monomers in the
copolymerization lead to three distinguish polymer chain
structures. When the two monomers are arranged in an alternating
fashion, the polymer is called an alternating copolymer:
-M1-M2-M1-M2-M1-M2-M1-M2-M1-M2-M1-M2-M1-M2
[0040] In a random copolymer, the two monomers are inserted in a
random order:
-M1-M1-M2-M1-M2-M2-M1-M2-M1-M1-M2-M2-M2-M1
[0041] In a block copolymer, one type of monomer is grouped
together in a chain segment, and another one is grouped together in
another chain segments. A block copolymer can be thought of as a
polymers with multiple chain segments with each segment consisting
of the same type of monomer:
-M2-M2-M2-M2-M1-M1-M1-M2-M2-M2-M1-M1-M1-M1
[0042] The classification of the three types of copolymers can be
also reflected in the reactivity ratio product, r.sub.1r.sub.2. As
is known to those skilled in the art, when r.sub.1r.sub.2=1, the
polymerization is called ideal copolymerization. Ideal
copolymerization occurs when the two types of propagating chains
M1* and M2* show the same preference for inserting M1 or M2
monomer. The copolymer is "statistically random." For the case,
where the two monomer reactivity ratios are different, for example,
r.sub.1>1 and r.sub.2<1 or r.sub.1<1 and r.sub.2>1, one
of the monomers is more reactive than the other toward both
propagating chains. The copolymer will contain a larger proportion
of the more reactive monomer in random placement.
[0043] When both r.sub.1 and r.sub.2 are greater than unity (and
therefore, also r.sub.1r.sub.2>1), there is a tendency to form a
block copolymer in which there are blocks of both monomers in the
chain. For the special case of r.sub.1>>r.sub.2 (i.e.
r.sub.1>>1 and r.sub.2<<1), both types of propagating
chains preferentially add to monomer M1. There is a tendency toward
"consecutive homopolymerization" of the two monomers to form block
copolymer. A copolymer having reactivity product, r.sub.1r.sub.2,
greater than 1.5 contains relatively long homopolymer sequences and
is said to be "blocky."
[0044] The two monomers enter into the copolymer in equi-molar
amounts in a nonrandom, alternating arrangement along the copolymer
chain when r.sub.1r.sub.2=0. This type of copolymerization is
referred to as alternating copolymerization. Each of the two types
of propagating chains preferentially adds to the other monomer,
that is, M1 adds only to M2* and M2 adds only to M1*. The copolymer
has the alternating structure irrespective of the co-monomer feed
composition.
[0045] The behavior of most copolymer systems lies between the two
extremes of ideal and alternating copolymerization. As the
r.sub.1r.sub.2 product decreases from unity toward zero, there is
an increasing tendency toward alternation. Perfect alternation will
occur when r1 and r2 become progressively less than unity. In other
words, a copolymer having a reactivity ratio product r.sub.1r.sub.2
of between 0.75 and 1.5 is generally said to be random. When
r.sub.1r.sub.2>1.5 the copolymer is said to be "blocky." The
first component of the invention has a reactivity ratio of less
than 0.75 and is therefore considered "alternating". The second
component of the invention has a reactivity ratio of greater than
or equal to 0.75 and is therefore considered "random".
[0046] The reactivity ratio product is described more fully in
Textbook of Polymer Chemistry, F. W. Billmeyer, Jr., Interscience
Publishers, New York, p. 221 et seq. (1957). For a copolymer of
ethylene and propylene, the reactivity ratio product
r.sub.1r.sub.2, where r.sub.1 is the reactivity ratio of ethylene
and r.sub.2 is the reactivity ratio of propylene, can be calculated
from the measured diad distribution (PP, EE, EP and PE in this
nomenclature) by the application of the following formulae:
r.sub.1r.sub.2=4 (EE)(PP)/(EP).sup.2.
[0047] The copolymers are preferably prepared using homogeneous
conditions, such as a continuous solution polymerization process.
In some embodiments, the copolymer are prepared in parallel
solution polymerization reactors, such that the first reactor
component is prepared in a first reactor and the second reactor
component is prepared in a second reactor, and the reactor effluent
from the first and second reactors are combined and blended to form
a single reactor effluent from which the final copolymer is
separated. Exemplary methods for the preparation of copolymers may
be found in U.S. Pat. Nos. 6,881,800; 7,803,876; 8,013,069; and
8,026,323 and PCT Publications WO 2011/087729; WO 2011/087730; and
WO 2011/087731, incorporated herein by reference.
[0048] Preferably, the first reactor component of the copolymer is
polymerized using a non-metallocene catalyst and the second reactor
component of the copolymer is polymerized using a metallocene
catalyst. The term "non-metallocene catalyst", also known as
"post-metallocene catalyst" describe transition metal complexes
that do not feature any pi-coordinated cyclopentadienyl anion
donors (or the like) and are useful the polymerization of olefins
when combined with common activators. See Baier, M. C.; Zuideveld,
M. A.; Mecking, S. Angew. Chem. Int. Ed. 2014, 53, 2-25; Gibson, V.
C., Spitzmesser, S. K. Chem. Rev. 2003, 103, 283-315; Britovsek, G.
J. P., Gibson, V. C., Wass, D. F. Angew. Chem. Int. Ed. 1999, 38,
428-447; Diamond, G. M. et al. ACS Catal. 2011, 1, 887-900; Sakuma,
A., Weiser, M. S., Fujita, T. Polymer J. 2007, 39:3, 193-207. See
also U.S. Pat. Nos. 6,841,502, 7,256,296, 7,018,949, 7,964,681.
[0049] Preferably, the first reactor component of the copolymer is
a pyridyl diamide catalyzed and the second reactor component of the
copolymer is metallocene catalyzed. The pyridyl diamide catalyst
has the following structural formula:
##STR00001##
wherein M is a Group 3-12 metal; E is selected from carbon,
silicon, or germanium; X is an anionic leaving group, such as, but
not limited to alkyl, aryl, hydride, alkylsilane, fluoride,
chloride, bromide, iodide, triflate, carboxylate, alkylsulfonate,
amide, alkoxide, and hydroxide; L is a neutral Lewis base, such as,
but not limited to ether, amine, thioether; and R.sup.13 are
independently selected from the group consisting of hydrocarbyls,
substituted hydrocarbyls, and silyl groups; R.sup.2 through
R.sup.12 are independently selected from the group consisting of
hydrogen, hydrocarbyls, alkoxy, silyl, amino, aryloxy, substituted
hydrocarbyls, halogen, and phosphino; n is 1 or 2 or 3; m is 0, 1,
or 2; and two X groups may be joined together to form a dianionic
group; two L groups may be joined together to form a bidentate
Lewis base; an X group may be joined to an L group to form a
monoanionic bidentate group; any two adjacent R groups (e.g.
R.sup.7 & R.sup.8, R.sup.10 & R.sup.11, etc.) may be joined
to form a substituted or unsubstituted hydrocarbyl or heterocyclic
ring, where the ring has 5, 6, 7, or 8 ring atoms and where
substitutions on the ring can join to form additional rings;
(preferably an aromatic ring, a six membered aromatic ring with the
joined R.sup.7R.sup.8 group being --CH.dbd.CHCH.dbd.CH--); and
R.sup.11 may be joined to form a ring (preferably a five membered
ring with the joined R.sup.10R.sup.11 group being
--CH.sub.2CH.sub.2--, a six membered ring with the joined
R.sup.10R.sup.11 group being --CH.sub.2CH.sub.2CH.sub.2--).
[0050] Preferably, M is a Group 4 metal, such as zirconium or
hafnium. Preferably, n is 2 and m is 0; Preferably, E is carbon.
Preferred X groups include chloride, fluoride, methyl, ethyl,
propyl, butyl, isobutyl, benzyl, hydrido, dialkylamido,
dimethylamido, diethylamido, trimethylsilylmethyl, and neopentyl.
Preferred R.sup.1 groups include aryls, substituted aryls,
2,6-disubstituted aryls, 2,4,6-trisubtituted aryls,
2,6-diisopropylphenyl, 2,4,6-triisopropylphenyl,
2,6-diisopropyl-4-methyl-phenyl, xylyl, mesityl, and
2-ethyl-6-isopropylphenyl. Preferred R.sup.13 groups include aryls,
substituted aryls, 2-substituted aryls, cycloalkyl, cyclohexyl,
cyclopentyl, 2,5-disubstituted aryl, 2-methylphenyl, 2-ethylphenyl,
2-isopropylphenyl, phenyl, and 4-methylphenyl. Preferred
R.sup.2/R.sup.3 pairs include H/H, H/aryl, H/2-substituted aryl,
H/alkyl, H/phenyl, H/2-methylphenyl, and H/2-isopropylphenyl.
[0051] In a preferred embodiment, both R.sup.7 and R.sup.8 are
hydrogen.
[0052] In a preferred embodiment, R.sup.7 and R.sup.8 are joined
together to form a six-membered aromatic ring.
[0053] In a preferred embodiment, R.sup.10 and R.sup.11 are joined
together to form a five or six-membered ring.
[0054] In a preferred embodiment, R.sup.11 and R.sup.12 are both
hydrogen.
[0055] In a preferred embodiment, R.sup.1 and R.sup.13 may be
independently selected from phenyl groups that are variously
substituted with between zero to five substituents that include F,
Cl, Br, I, CF.sub.3, NO.sub.2, alkoxy, dialkylamino, aryl, and
alkyl groups having 1 to 10 carbons, such as methyl, ethyl, propyl,
butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, and isomers
thereof.
[0056] Preferred R.sup.3-E-R.sup.2 groups and preferred
R.sup.12-E-R.sup.11 groups include CH.sub.2, CMe.sub.2, SiMe.sub.2,
SiEt.sub.2, SiPr.sub.2, SiBu.sub.2, SiPh.sub.2, Si(aryl).sub.2,
Si(alkyl).sub.2, CH(aryl), CH(Ph), CH(alkyl), and
CH(2-isopropylphenyl), where alkyl is a C.sub.1 to C.sub.40 alkyl
group (preferably C.sub.1 to C.sub.20 alkyl, preferably one or more
of methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl,
nonyl, decyl, undecyl, dodecyl, and isomers thereof), aryl is a
C.sub.5 to C.sub.40 aryl group (preferably a C.sub.6 to C.sub.20
aryl group, preferably phenyl or substituted phenyl, preferably
phenyl, 2-isopropylphenyl, or 2-tertbutylphenyl).
[0057] Examples of suitable metallocene catalysts for polymerizing
the second component include those of capable of producing
crystalline poly-alpha-olefins, such as crystalline propylene
homopolymers and semi-crystalline propylene copolymers, include
those obeying the following general formula (1):
##STR00002##
wherein M is a Group 3, 4, 5 or 6 transition metal atom, or a
lanthanide metal atom, or actinide metal atom, preferably a Group 4
transition metal atom selected from titanium, zirconium or hafnium;
each cyclopentadienyl (Cp) ring is substituted with from zero to
four substituent groups S.sub.v, each substituent group S.sub.v
being, independently, a hydrocarbyl, substituted-hydrocarbyl,
halocarbyl, substituted-halocarbyl, hydrocarbyl-substituted
organometalloid, halocarbyl-substituted organometalloid,
disubstituted boron, disubstituted pnictogen, substituted chalcogen
or halogen radical, provided that two adjacent S.sub.v groups may
be joined to form a C.sub.4 to C.sub.20 ring to give a saturated or
unsaturated polycyclic ligand, wherein the subscript "v" denotes
the carbon atom on the Cp-ring to which the substituent is bonded;
A is a bridging group; and X.sub.1 and X.sub.2 are, independently,
hydride radicals, hydrocarbyl radicals, substituted hydrocarbyl
radicals, halocarbyl radicals, substituted halocarbyl radicals, and
hydrocarbyl- and halocarbyl-substituted organometalloid radicals,
substituted pnictogen radicals, or substituted chalcogen radicals;
or X.sub.1 and X.sub.2 are joined and bound to the metal atom to
form a metallacycle ring containing from about 3 to about 20 carbon
atoms; or X.sub.1 and X.sub.2 together can be an olefin, diolefin
or aryne ligand; or when Lewis-acid activators, such as
methylalumoxane, which are capable of donating an X.sub.1 ligand as
described above to the transition metal component are used, X.sub.1
and X.sub.2 may independently be a halogen, alkoxide, aryloxide,
amide, phosphide or other univalent anionic ligand or both X.sub.1
and X.sub.2 can also be joined to form a anionic chelating ligand
and with the proviso that X.sub.1 and X.sub.2 are not a substituted
or unsubstituted cyclopentadienyl ring.
[0058] Conveniently, A is a bridging group containing boron or a
Group 14, 15 or 16 element. Examples of suitable bridging groups
include R'.sub.2C, R'.sub.2Si, R'.sub.2CCR'.sub.2,
R'.sub.2CCR'.sub.2CR'.sub.2, R'.sub.2CCR'.sub.2CR'.sub.2CR'.sub.2,
R'C.dbd.CR', R'C.dbd.CR'CR'.sub.2, R'.sub.2CCR'.dbd.CR'CR'.sub.2,
R'C.dbd.CR'CR'.dbd.CR', R'C.dbd.CR'CR'.sub.2CR'.sub.2,
R'.sub.2CSiR'.sub.2, R'.sub.2SiSiR'.sub.2,
R'.sub.2CSiR'.sub.2CR'.sub.2, R'.sub.2SiCR'.sub.2SiR'.sub.2,
R'C.dbd.CR'SiR'.sub.2, R'.sub.2CGeR'.sub.2, R'.sub.2GeGeR'.sub.2,
R'.sub.2CGeR'.sub.2CR'.sub.2, R'.sub.2GeCR'.sub.2GeR'.sub.2,
R'.sub.2SiGeR'.sub.2, R'C.dbd.CR'GeR'.sub.2, RB, R'.sub.2C--BR',
R'.sub.2C--BR--CR'.sub.2, RN, R'P, O, S, Se,
R'.sub.2C--O--CR'.sub.2, R'.sub.2CR'.sub.2C--O--CR.sub.2CR.sub.2,
R'.sub.2C--O--CR'.sub.2CR'.sub.2, R'.sub.2C--O--CR'.dbd.CR',
R'.sub.2C--S--CR'.sub.2, R'.sub.2CR'.sub.2C--S--CR'.sub.2CR'.sub.2,
R'.sub.2C--S--CR'.sub.2CR'.sub.2, R'.sub.2C--S--CR'.dbd.CR',
R'.sub.2C--Se--CR'.sub.2,
R'.sub.2CR'.sub.2C--Se--CR'.sub.2CR'.sub.2,
R'.sub.2C--Se--CR'.sub.2CR'.sub.2, R'.sub.2C--Se--CR'.dbd.CR',
R'.sub.2C--N.dbd.CR', R'.sub.2C--NR--CR'.sub.2,
R'.sub.2C--NR'--CR'.sub.2CR'.sub.2, R'--NR'--CR'.dbd.CR',
R'--NR'--CR'.sub.2CR'.sub.2, R'.sub.2C--P.dbd.CR', and
R'.sub.2C--PR'--CR' where R is hydrogen or a C.sub.1-C.sub.20
containing hydrocarbyl, substituted hydrocarbyl, halocarbyl,
substituted halocarbyl, silylcarbyl or germylcarbyl substituent and
optionally two or more adjacent R may join to form a substituted or
unsubstituted, saturated, partially unsaturated or aromatic, cyclic
or polycyclic substituent. Preferred examples for the bridging
group A include CH.sub.2, CH.sub.2CH.sub.2, CH(CH.sub.3).sub.2, O,
S, SiMe.sub.2, SiPh.sub.2, SiMePh, Si(CH.sub.2).sub.3 and
Si(CH.sub.2).sub.4.
[0059] Preferred transition metal compounds for producing
poly-alpha-olefins having enhanced isotactic character are those of
formula 1 where the S.sub.v groups are independently chosen such
that the metallocene framework 1) has no plane of symmetry
containing the metal center, and 2) has a C.sub.2-axis of symmetry
through the metal center. These complexes, such as
rac-Me.sub.2Si(indenyl).sub.2ZrMe.sub.2 and
rac-Me.sub.2Si(indenyl).sub.2HfMe.sub.2, are well known in the art
and generally produce isotactic polymers with high degrees of
stereoregularity.
[0060] Preferred metallocene catalysts useful for producing the
second polymer in the process of the invention are not narrowly
defined but generally it is found that the most suitable are those
in the generic class of bridged, substituted bis(cyclopentadienyl)
metallocenes, specifically bridged bis(indenyl) metallocenes.
Preferably, useful metallocene compounds having two
cyclopentadienyl rings are represented by the formula:
##STR00003##
wherein: M is the same as M described above, preferably M is
titanium, zirconium or hafnium, Zr or Hf; Z and Q* are,
independently, a substituted or unsubstituted Cp group (useful Z
and Q* groups are represented by the formula:
(C.sub.5H.sub.4-dS*.sub.d), where d is 1, 2, 3, or 4, S* is
hydrocarbyl groups, heteroatoms, or heteroatom-containing groups,
such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl,
nonyl, decyl, undecyl, dodecyl, or an isomer thereof, N, O, S, P,
or a C.sub.1 to C.sub.20 hydrocarbyl substituted with an N, O, S
and or P heteroatom or heteroatom-containing group (typically
having up to 12 atoms, including the N, O, S, and P heteroatoms)
and two S* may form a cyclic or multicyclic group; T is a bridging
group as described above that is bonded to Z and Q*, y is zero or
one; and each X is, independently, a univalent anionic ligand, or
two X are joined and bound to the metal atom to form a metallocycle
ring, or two X are joined to form a chelating ligand, a diene
ligand, or an alkylidene ligand provided that when y is one then at
least one of Z and Q* is preferably not an indene group,
alternately, both of Z and Q* are not indene. In an alternate
embodiment, when y is one, Z and Q* are not 2,4 substituted indene,
preferably are not 2-methyl, 4-phenyl indene. Example of
bis(indenyl) metallocenes compound includes .mu.-(CH3)2
Si(indenyl)2 Hf(Cl)2 and .mu.-(CH3)2 Si(indenyl)2 Hf(CH3)2.
[0061] The activators for these metallocene catalysts can
methylaluminoxane (MAO), or a non-coordinating anion activator
selected from the group consisting of dimethylanilinium- or
trityl-fluoroarylborates, wherein the fluoroaryl group is
pentafluorophenyl, perfluoronaphthyl, or
quadrafluoro-trihydronaphthyl.
[0062] As used in this document, the term "room temperature" is
used to refer to the temperature range of about 20.degree. C. to
about 23.5.degree. C.
[0063] The propylene-olefin copolymer can be made using general
polymerization techniques known in the art. Any solution,
suspension, slurry and bulk and gas phase polymerization process
known in the art can be used. Such processes can be run in batch,
semi-batch or continuous mode. Homogeneous solution processes are
preferred.
[0064] In a typical solution process, catalyst components, solvent,
monomers and hydrogen (when used) are fed under pressure to one or
more reactors. The temperature of the reactor is controlled by the
rate of catalyst addition (rate of polymerization), the temperature
of the solvent/monomer feed stream and/or the use of heat transfer
systems. For olefin polymerization, reactor temperatures can range
from about 60.degree. C. to about 250.degree. C., while pressures
are generally higher than 300 psig. In one embodiment, the
polymerization temperature is preferably at least 50, or 60, or
70.degree. C., or within a range from 50, or 60, or 70, or 80, or
90, or 100, or 120 to 130, or 140, or 150, or 160, or 170.degree.
C.
[0065] The monomers are dissolved/dispersed in the solvent either
prior to being fed to the first reactor (or for gaseous monomers
the monomer may be fed to the reactor so that it will dissolve in
the reaction mixture). Prior to mixing, the solvent and monomers
are generally purified to remove potential catalyst poisons. The
feedstock may be heated or cooled prior to feeding to the first
reactor. Additional monomers and solvent may be added to the second
reactor, and it may be heated or cooled. The catalysts/activators
can be fed in the first reactor or split between two reactors. In
solution polymerization, polymer produced is molten and remains
dissolved in the solvent under reactor conditions, forming a
polymer solution (also referred as to effluent).
[0066] The solution polymerization process of this invention uses
stirred reactor system comprising one or more stirred
polymerization reactors. Generally the reactors should be operated
under conditions to achieve a thorough mixing of the reactants. In
a dual reactor system, the first polymerization reactor preferably
operates at lower temperature. The residence time in each reactor
will depend on the design and the capacity of the reactor. The
catalysts/activators can be fed into the first reactor only or
split between two reactors. Alternatively, a loop reactor is
preferred.
[0067] The polymer solution is then discharged from the reactor as
an effluent stream and the polymerization reaction is quenched,
typically with coordinating polar compounds, to prevent further
polymerization. On leaving the reactor system the polymer solution
is passed through a heat exchanger system on route to a
devolatilization system and polymer finishing process. Under
certain conditions of temperature and pressure, the polymer
solution can phase separate into a polymer lean phase and a polymer
rich phase. Phase separation occurs at the lower critical solution
temperature (LCST). Increasing the temperature or decreasing the
pressure at the LCST point leads to further phase separation.
[0068] A polymer can be recovered from the effluent of either
reactor or the combined effluent, by separating the polymer from
other constituents of the effluent. Conventional separation means
may be employed. For example, polymer can be recovered from
effluent by coagulation with a non-solvent such as isopropyl
alcohol, acetone, or n-butyl alcohol, or the polymer can be
recovered by stripping the solvent or other media with heat or
steam. One or more conventional additives such as antioxidants can
be incorporated in the polymer during the recovery procedure.
Possible antioxidants include phenyl-beta-naphthylamine;
di-tert-butylhydroquinone, triphenyl phosphate, heptylated
diphenylamine, 2,2'-methylene-bis(4-methyl-6-tert-butyl)phenol, and
2,2,4-trimethyl-6-phenyl-1,2-dihydroquinoline. Other methods of
recovery such as by the use of lower critical solution temperature
(LCST) followed by devolatilization are also envisioned.
[0069] Preferably, the propylene-olefin copolymer described herein
is produced in either batch or continuous multistage polymerization
processes. Each polymerization stage is defined as a single
polymerization reactor or a polymerization zone within a single
reactor. More specifically, a multistage polymerization may involve
either two or more sequential polymerizations (also referred to as
a series process) or two or more parallel polymerizations (also
referred to herein as a "parallel process"). Preferably, the
polymerization is conducted in a parallel process.
[0070] Each component of the propylene-olefin copolymer made in the
respective reactors of the continuous, multiple reactor solution
process are blended in solution without prior isolation from the
solvent. The blends may be a result of series reactor operation,
where at least part of the effluent of a first reactor enters a
second reactor and where the effluent of the second reactor can be
submitted to finishing steps involving devolatilization. The blend
may also be the result of parallel reactor operation where the
effluents of both reactors are combined and submitted to finishing
steps. Either option provides an intimate admixture of the polymers
in the devolatilized copolymers. Either case permits a wide variety
of polysplits to be prepared whereby the proportion of the amounts
of each component produced in the respective reactors can be varied
widely.
[0071] Preferably, the propylene-olefin copolymer is a reactor
blend. The method discussed herein has the advantage of eliminating
the need for a melt blending operation and enables intimate blends
of the copolymers to be made in the original reaction medium. Such
materials have unique properties because they are not subjected to
shear degradation in melt processing equipment. The degree of
mixing of each component of the blend is more intimate.
[0072] Disclosed herein are continuous processes for making the
propylene-olefin copolymer. The process comprises contacting
monomers including ethylene and propylene with a catalyst system in
a first polymerization zone, thereby forming a mixture that
includes the propylene copolymers, said first propylene copolymer
having an ethylene content of about 15 to about 20 wt %;
polymerizing in a second polymerization zone by contacting a second
monomer system and a second catalyst system capable of providing
propylene copolymer, said second propylene copolymer having an
ethylene content of about 6 to about 10 wt %. Preferably the said
second catalyst is different from the first catalyst system.
[0073] In one example of a parallel process, two reactors are
configured such that monomers, catalyst(s) and solvent are fed
independently to each reactor. The first and second polymerizations
are preferably taking place simultaneously in a parallel
process.
[0074] The molecular weight characteristics (e.g., Mw, Mn, etc.) of
the propylene-olefin copolymer and also of the individual-propylene
copolymer components can in certain circumstances be adjusted
depending upon the desired properties of the propylene-olefin
copolymer. Those molecular weight characteristics are described
elsewhere herein. For example, the molecular weight characteristics
of each polymer can be set by choosing the reactor temperature,
monomer concentration, and by optionally adding chain transfer
agents such as hydrogen. Also, molecular weight can generally be
lowered by increasing reaction temperatures, and raised by
increasing monomer concentrations.
[0075] The propylene olefin copolymer may be used to prepare
nonwoven elastic articles. The nonwoven products described above
may be used in articles such as hygiene products, including, but
not limited to, diapers, feminine care products, and adult
incontinent products. The nonwoven products may also be used in
medical products such as a sterile wrap, isolation gowns, operating
room gowns, surgical gowns, surgical drapes, first aid dressings,
and other disposable items. In particular, the nonwoven products
may be useful as facing layers for medical gowns, and allow for
extensibility in the elbow area of the gown. The nonwoven products
may also be useful in disposable protective clothing, and may add
toughness to elbow and knee regions of such clothing. The nonwoven
products may also be useful as protective wrapping, packaging, or
wound care. The nonwoven products may also be useful in geotextile
applications, as the fabric may have improved puncture resistance
in that the fabric will deform instead of puncture. See U.S. Patent
Publication No. 2011/81529 and U.S. Pat. No. 7,319,077. The
propylene olefin copolymer may also be suitable for use in an
elastic films, as described in U.S. Pat. No. 6,500,563; blow films,
as described in U.S. Patent Publication No. 2009/94027; and
cast-films, as described in U.S. Pat. No. 7,655,317. In an
embodiment of the invention, the nonwoven elastic article has a
basis weight in the range of about 5 to about 100 gsm, preferably
15 to 75 gsm, preferably 20 to 50 gsm. In an embodiment of the
invention, the nonwoven elastic article is a film having a gauge in
the range of about 5 to about 100 .mu.m, preferably 15 to 75 .mu.m,
preferably 20 to 50 .mu.m.
[0076] The propylene olefin copolymer has suitable elastic
properties for use in nonwoven articles, including low tension set,
top load, and hysteresis, and high retractive force. The method of
measurement for evaluating these elastic properties is described in
the Examples section below. In an embodiment, the tension set of
the copolymer is less than about 25%, preferably less than about
20%, most preferably less than about 15%. In an embodiment, the top
load of the copolymer is less than about 15 N, preferably less than
about 10 N, most preferably less than about 8 N. In an embodiment,
the retractive force is greater than about 1 N, preferably greater
than about 2 N, and most preferably greater than about 3.5 N. In an
embodiment, the hysteresis of the copolymer is less than about 45%,
preferably less than about 40%, most preferably less than about
35%. In an embodiment, the copolymer of the invention has at least
one of the above-mentioned properties. In an embodiment, the
copolymer of the invention has one or more of the above-mentioned
properties, in any combination thereof.
[0077] The disclosure will now be more particularly described with
reference to the following Examples.
EXAMPLES
Comparative Example 1 (CE1)
[0078] CE1 is a reactor blended propylene-based elastomer where the
major component has 16 wt % ethylene content and 3 MFR (Mw of
240,000 g/mol) and the minor component has 4 wt % ethylene and 8
MFR (Mw of 195,000 g/mol). Both the first and second components of
CE1 have an r1r2 of about 0.8 to about 0.9. CE1 is made in a
reactor using C2-symmetric metallocene catalyst of dimethylsilyl
bis(indenyl) hafnium dimethyl precursor activated by
dimethylanilinium tetrakis(heptafluoronaphthyl) borate. CE1 was
selected as the comparable example for its good elasticity.
Example 1 (E1)
[0079] E1 is a solution blend of 80 wt % component (i)
(propylene-ethylene copolymer having 15.7 wt % ethylene content and
a weight average molecular weight of 531,000 g/mol) and 20 wt %
component (ii) (propylene-ethylene copolymer having 9.8 wt %
ethylene content and a weight average molecular weight of 22,000
g/mol). 8 grams of component (i) and 2 grams of component (ii) were
placed in a 500 mL round bottom flask. 400 mL of xylene and a
magnetic stirrer was added to the flask. The flask was placed on an
IKA hot plate with a stirrer, set at a stir rate of 250 rpm. The
solution was stirred for 14-16 hours after which the temperature
was raised to 130.degree. C. and the solution was stirred at this
temperature for an additional 6 hours. The stir rate was raised to
800 rpm for the final 5 minutes. The hot solution was then poured
into a large glass evaporation dish. The flask was washed with
30-40 mL of hot xylene three times and the wash was added to the
evaporating dish. The solution was cooled for an hour at room
temperature in a general purpose hood. The dish was then placed in
a vacuum oven with nitrogen purge and a solvent trap. The oven was
set at 50.degree. C. and the solution was dried under vacuum for 48
hours.
[0080] E1 component (i) was polymerized using a Cl symmetric
2,6-diisopropyl-N-((6-(2-((o-tolylamido)methyl)naphthalen-1-yl)pyridin-2--
yl)methyl)anilidohafnium dimethyl precursor activated by
dimethylanilinium tetrakis(pentafluorophenyl) borate.
Polymerizations were carried out in a continuous stirred tank
reactor system. A 1-liter Autoclave reactor was equipped with a
stirrer, a pressure controller, and a water cooling/steam heating
element with a temperature controller. The reactor was operated in
liquid fill condition at a reactor pressure in excess of the
bubbling point pressure of the reactant mixture, keeping the
reactants in liquid phase. All feeds (solvent and monomers) were
pumped into the reactors by Pulsa feed pumps and the flow rates
were controlled using Coriolis mass flow controller (Quantim series
from Brooks) except for the ethylene, which flowed as a gas under
its own pressure through a Brooks flow controller. Similarly, H2
feed was controlled using a Brooks flow controller. Ethylene, H2
and propylene feeds were combined into one stream and then mixed
with a pre-chilled isohexane stream that had been cooled to at
least 0.degree. C. The mixture was then fed to the reactor through
a single line. Scavenger solution was added to the combined solvent
and monomer stream just before it entered the reactor to further
reduce any catalyst poisons. Similarly, catalyst solution was fed
to the reactor using an ISCO syringe pump through a separated
line.
[0081] Isohexane (used as solvent), and monomers (e.g., ethylene
and propylene) were purified over beds of alumina and molecular
sieves. Toluene for preparing catalyst solutions was purified by
the same technique.
[0082] An isohexane solution of tri-n-octyl aluminum (TNOA) (25 wt
% in hexane, Sigma Aldrich) was used as scavenger solution.
2,6-diisopropyl-N-((6-(2-((o-tolylamido)methyl)naphthalen-1-yl)pyridin-2--
yl)methyl)anilidohafnium dimethyl was activated with N,N-dimethyl
anilinium tetrakis (pentafluorophenyl) borate at a molar ratio of
about 1:1 in 900 ml of toluene.
[0083] The polymer produced in the reactor exited through a back
pressure control valve that reduced the pressure to atmospheric.
This caused the unconverted monomers in the solution to flash into
a vapor phase which was vented from the top of a vapor liquid
separator. The liquid phase, comprising mainly polymer and solvent,
was collected for polymer recovery. The collected samples were
first air-dried in a hood to evaporate most of the solvent, and
then dried in a vacuum oven at a temperature of about 90.degree. C.
for about 12 hours. The vacuum oven dried samples were weighed to
obtain yields.
[0084] The scavenger feed rate was adjusted to optimize the
catalyst efficiency and the feed rate varied from 0 (no scavenger)
to 15 .mu.mol/min. The catalyst feed rates may also be adjusted
according to the level of impurities in the system to reach the
targeted conversions listed. All the reactions were carried out at
a pressure of about 2.4 MPa/g unless otherwise mentioned. The
reaction temperature was 70.degree. C. with feed rates of 14 g/min
for propylene, 0.9 g/min for ethylene, 2.41 ml/min for H2, and 56.7
g/min for isohexane. The overall conversion was 32.9 wt %.
[0085] E1 component (ii) was polymerized using a C2-symmetric
metallocene catalyst of dimethylsilyl bis(indenyl) hafnium dimethyl
precursor activated by dimethylanilinium
tetrakis(heptafluorophenyl) borate. This material was also made in
a continuous stirred tank reactor by following the same procedure
as used for E1 component (i), except that a 1-liter Autoclave
reactor was used. The catalyst was pre-activated with the activator
at a molar ratio of about 1:1 in 900 mL of toluene. All catalyst
solutions were kept in an inert atmosphere and fed into reactors
using an ISCO syringe pump. TNOAL solution was further diluted in
isohexane and used as a scavenger. Scavenger feed rate was adjusted
to maximize the catalyst efficiency. The reaction was carried out
at a temperature of 115.degree. C., propylene feed rate of 14.58
g/min, an ethylene feed rate of 1 g/min, and isohexane feed rate of
59.4 g/min. The overall conversion was 55.5 wt %.
Example 2 (E2)
[0086] E2 is a blend of 80 wt % of component (i)
(propylene-ethylene copolymer having 20.2 wt % ethylene and a
weight average molecular weight of 717,000 g/mol) and 20 wt % of
component (ii) (propylene-ethylene copolymer having 9.8 wt %
ethylene and a weight average molecular weight of 22,000 g/mol). 8
grams of component (i) and 2 grams of component (ii) were placed in
a 500 mL round bottom flask. 400 mL of xylene was added to the
flask, with a magnetic stirrer. The flask was placed on an IKA hot
plate and the stirrer was set at a 250 rpm stir rate. The solution
was stirred for 14-16 hours after which the temperature was raised
to 130.degree. C. and the solution was stirred at this temperature
for 6 additional hours. The stir rate was raised to 800 rpm for the
final 5 minutes. The hot solution was then poured into a large
glass evaporation dish. The flask was washed with about 30-40 mL of
hot xylene three times and the wash added to the evaporating dish.
The solution was cooled for an hour at room temperature in a
general purpose hood. The dish was then placed in a vacuum oven
with nitrogen purge and a solvent trap. The oven was set at
50.degree. C. and the solution was dried under vacuum for 48
hours.
[0087] E2 component (i) was polymerized by following the same
procedure as used for E1 component (i), described above. The
polymerization reaction was carried out at a temperature of
70.degree. C., a propylene feed rate of 14 g/min, ethylene feed
rate of 0.9 g/min, H2 feed rate of 2.41 scc/min (H2 was diluted
with N.sub.2) and isohexane feed rate of 56.7 g/min. The overall
conversion was 27.5 wt %. E2 component (ii) is the same as E1
component (ii).
Example 3 (E3)
[0088] E3 is a blend of 80 wt % of component (i)
(propylene-ethylene copolymer with 16.0 wt % ethylene and a weight
average molecular weight of 686,000 g/mol) and 20 wt % of component
(ii) (propylene-ethylene copolymer with 9.8 wt % ethylene and a
weight average molecular weight of 22,000 g/mol). 8 grams of
component (i) and 2 grams of component (ii) were placed in a 500 mL
round bottom flask. 400 mL of xylene was added to the flask with a
magnetic stirrer. The flask was placed on an IKA hot plate and
stirrer, set at a 250 rpm stir rate. The solution was allowed to
stir for 14-16 hours after which the temperature was raised to
130.degree. C. and the solution was stirred at this temperature for
6 additional hours. The stir rate was raised to 800 rpm for the
final 5 minutes. The hot solution was then poured into a large
glass evaporation dish. The flask was washed with about 30-40 mL of
hot xylene three times and the wash added to the evaporating dish.
The solution was cooled for an hour at room temperature in a
general purpose hood. The dish was then placed in a vacuum oven
with nitrogen purge and a solvent trap. The oven was set at
50.degree. C. and the solution was dried under vacuum for 48
hours.
[0089] E3 component (i) was polymerized by following the same
procedure as used for E1 component (i). The reaction was carried
out at a temperature of 85.degree. C., propylene feed rate of 14
g/min, ethylene feed rate of 0.9 g/min and isohexane feed rate of
56.7 g/min. The overall conversion was 31.8 wt %.
[0090] E3 component (ii) is identical to E1 component (ii).
Characterization of CE1, E1, E2, and E3 Components
TABLE-US-00001 [0091] TABLE 1 COMPOSITION CHARACTERIZATION RESULTS
MFR C.sub.2 g/10 Mw x-ray Sample wt % min kg/mol PDI r1r2 % mm
crystal.sup.2 CE1 14.7 3 248 1.7 0.85 88.5 10% E1(i) 15.7 <1 531
2.0 0.59 94.7 3% E2(i) 20.2 <1 717 2.0 0.54 99.9 <0.5%.sup.
E3(i) 16.0 <1 686 1.7 0.59 95.6 1% E1/2/3(ii) 9.7 N/A 22 2 2
0.87 82.2 22% .sup.1Crystallizable sequence .sup.2Crystallinity
determined by x-ray after aging for a minimum of 7 days
Solution Blending
[0092] 80 wt % E1(i) and 20 wt % E1(ii); 80 wt % E2(i) and 20 wt %
E2(ii); and 80 wt % E3(i) and 20 wt % E3(ii) were solution blended
in xylene at 130.degree. C. by the process described above. The
resulting blend was compression molded using a Fontijne melt vacuum
press and aged for a minimum of 7 days after molding before the
mechanical testing, described below, was conducted.
Elastic Properties of CE1, E1, E2, and E3 Blends
[0093] A Fontijne melt vacuum press was used to mold a 2 mm thick
plaque of each sample. The temperature was ramped up to 190.degree.
C. and held for 5 minutes followed by 5 minutes under compression
before cooling to room temperature. ASTM type 3 dog bones were
punched simultaneously using a gang die and clicker press. The
sample was aged for a minimum of 7 days after molding before tests
were performed, to ensure that the samples which slowly crystallize
arrive at their final crystallinity. An Instron tensile tester was
used for the mechanical tests. The sample was placed in the grips
with a 35 mm grip separation. Slack was manually removed so that
the reading on the instrument registered a positive tensile force
before starting the test. The sample was stretched to a 100%
extension at 100 mm/min. The crosshead returned to 0% extension.
The cycle was repeated. The elasticity, top load, permanent set,
hysteresis, averaged over measurements are reported in Table 2
during the first and second cycles of loading.
[0094] All three bimodal blends (E1, E2 and E3) have favorably
lower set, top load, and hysteresis as compared to CE1.
TABLE-US-00002 TABLE 2 ELASTIC PROPERTIES Retrac- 2nd 2nd 2nd 1st
Top tive Hyster- 2nd Top Retrac- Hyster- Sam- set load Force esis
set load tive esis ple (%) (N) (N) (%) (%) (N) (N) (%) CE1 13.0
11.5 6.6 36.7 4.9 7.8 6.0 14.5 E1 10.3 6.5 4.1 29.0 3.0 4.6 3.8
10.4 E2 17.8 4.4 2.2 29.0 7.4 3.1 2.1 17.9 E3 13.1 5.6 3.4 29.0 5.9
4.2 3.2 13.2
Crystallization of Blends
[0095] A series of thermal experiments were performed using a TA
Instruments Differential Scanning calorimeter (DSC). The 2.sup.nd
Heat Flow curve was used to indicate how much of the sample had
crystallized over a select period of time at room temperature. The
time at isotherm ranged from a short period of 5 min to a maximum
period of 600 min Approximately 4 mg of each sample was weighed and
recorded for each isotherm. For each sample, 11 DSC pans were made
(for each isotherm) and each pan had a distinct crystallization
time, tc, from a melt at 200.degree. C. Per the heat-cool-heat
cycle, each sample started at room temperature and was heated to
200.degree. C. Once the high temperature was achieved, the sample
was held at that temperature for a period of 10 min, before
undergoing a rapid quench (50.degree. C./min) to bring the sample
back to room temperature. It is at this moment in the procedure
that each pan (for each sample) was to be held for a specific tc
value. After the time at the isotherm is achieved, the second melt
(10.degree. C./min to 200.degree. C.) was performed. The second
melt establishes the degree at which the samples melt, based upon
the crystallinity from the isotherms held at room temperature.
[0096] The FIGURE shows the enhanced crystallization kinetics of
blended materials, E1 and E3, over the comparative example CE1. The
DSC data show the overall heat flow on the second melt, that is,
after crystallizing at room temperature for a given time (tc). The
greater the heat flow, the higher the crystallinity. E1 and E3 show
an enhanced nucleation effect in crystallinity: after 20 minutes,
greater crystallinity were achieved (as measured from 2.sup.nd melt
after holding at room temperature at 20 mins). After about 90
minutes, E1 and E3 achieved substantially higher crystallinity than
CE1. Faster crystallization in such materials is known to aid
pellet stability.
[0097] Certain embodiments and features have been described using a
set of numerical upper limits and a set of numerical lower limits.
It should be appreciated that ranges from any lower limit to any
upper limit are contemplated unless otherwise indicated. Certain
lower limits, upper limits and ranges appear in one or more claims
below. All numerical values are "about" or "approximately" the
indicated value, and take into account experimental error and
variations that would be expected by a person having ordinary skill
in the art.
[0098] Various terms have been defined above. To the extent a term
used in a claim is not defined above, it should be given the
broadest definition persons in the pertinent art have given that
term as reflected in at least one printed publication or issued
patent. Furthermore, all patents, test procedures, and other
documents cited in this application are fully incorporated by
reference to the extent such disclosure is not inconsistent with
this application and for all jurisdictions in which such
incorporation is permitted.
[0099] While the foregoing is directed to embodiments of the
present invention, other and further embodiments of the invention
may be devised without departing from the basic scope thereof, and
the scope thereof is determined by the claims that follow.
* * * * *